One of the most amazing star systems in the galaxy is only 7500 light-years away. In the 1800s, it shined brighter than only one other star in the entire night sky. And combined, its two stars are at least five million times brighter than the Sun. Yet no one has ever seen either star directly – they’re encased in a cocoon of their own making.

Eta Carinae appears to consist of two supergiants. One of them may be a hundred times the mass of the Sun – one of the heaviest stars yet discovered. The other is perhaps 30 times the Sun’s mass or more.

Almost two centuries ago, the system began to flare up. Astronomers still aren’t quite sure why. Perhaps one of the stars engulfed a third member of the system. Or perhaps the two stars passed especially close together, and their gravity ripped out big torrents of hot gas.

Whatever the reason, over a couple of decades Eta Carinae grew especially bright. Then it faded from view. That’s because the two stars had expelled a huge amount of gas – enough to make 20 stars like the Sun. The material cooled, wrapping the stars in a dense nebula. It’s shaped like an hourglass, with a sheet extending from its waist like a ballerina’s tutu

The stars are only about three million years old. But the heavier one could expire at any time. It could explode as an especially bright supernova. Or it might collapse to form a black hole – a dark fate for a brilliant star.

Script by Damond Benningfield